Matrices on System Forms

When will we have the ability to add matrices to system forms?

I have been asked to produce an activity management system as a tab on the Sales Opportunity screen with ticklers/alerts tied to the alert management screen to notify staff when to revisit the oppportunity. This will be used to manage work associated with an opportunity both before and after the sale. They also want template activities to apply to this management tab. Therefore, I would like to create my own line-level data model and then implement the system with a matrix without having to recode all the functionality contained within and supporting the system Sales Opportunity screen.

Maybe there is an alternative way to consider doing this. Any ideas? Or, am I stuck....?

Scott